Michael –
Watch the young grasshoppers closely. Many growers have commented that the nymphs “just disappeared” the following year after application of Semaspore Bait — the infection does carry over from year to year in the egg pods. Another approach, especially when infestations are high, is to make smaller, more frequent applications of the bait. It’s a numbers game… the more you can get to eat the bait the better your results will be.
Applications made to younger grasshoppers will result in increased mortality with less carry-over to future hatches. Applications to older grasshoppers will result in less mortality but a greater carry-over into the next season. We recommend applications be made when grasshoppers are in their 3rd instar — about 1/4 in. long — to maximize both reduced numbers (50%) and spread of the infection to additional hatches.
https://www.planetnatural.com/pest-problem-solver/lawn-pests/grasshopper-control/
https://www.planetnatural.com/grasshopper-bait/
Hope this helps!